fix: add tomli dependency for Python 3.10 compatibility

- Add tomli>=2.0 as conditional dependency for Python < 3.11
- Fix test_edge_cases.py to use try/except import for tomllib/tomli
- This fixes CI failures on Python 3.10 where tomllib is not in stdlib

Author: Dev Engineer

pyproject.toml

@@ -38,6 +38,7 @@ dev = [
     "pytest>=7.0",
     "pytest-cov>=4.0",
     "ruff>=0.4.0",
+    "tomli>=2.0; python_version < '3.11'",
 ]
 # Duplicate license entries removed.
 

tests/test_edge_cases.py

@@ -9,7 +9,10 @@
 from io import StringIO
 from pathlib import Path
 
-import tomllib
+try:
+    import tomllib
+except ImportError:
+    import tomli as tomllib
 from rich.console import Console
 
 from deploydiff.cli import _load_plan, _render_costs